The mouth or pour opening in a container formed primarily of paper or plastic is generally sealed by covering the opening in the container with a film-like sheet or a pull-tab made of a resin. To open the container opening, the sheet or pull-tab is peeled or a straw is inserted through the sheet to pierce the sheet.
This use of a sheet which is peeled off the container or a pull-tab which is pierced with a straw does, however, present certain disadvantages and drawbacks. In one respect, the sheet, pull-tab and straw constitute rubbish separate and apart from the container itself and such items are liable to be easily thrown away.
There are containers in which only part of the sheet or pull-tab is peeled so that they are not completely separated from the containers. These containers have a problem because, when the sheet or pull-tab is released after opening, the mouth or opening in the container can be blocked by the released sheet or pull-tab. In containers made of a metal such as aluminum, a mouth structure is known in which, once the container is opened, the opened state is held. However, containers which are formed mainly of a paper or a plastic and which have such a mouth structure are not available. Thus, a need exists for a device which is adapted to be mounted on a container made primarily of paper or plastic and which serves as a mouth or pouring arrangement for the container.